The present invention relates to a closed circuit blade cooled turbine for improving the performance of gas turbine equipment by supplying a refrigerant inside the moving blades of a turbine, circulating and collecting it.
A conventional turbine moving blade cooling system is generally a closed circuit blade cooling system for warming or cooling a wheel which is a holding member of the moving blades first by introducing air extracted from an optional stage of a multistage compressor to a rotor which is a multistage turbine group, moderates the temperature gradient generated in the wheel, and then cooling and lowering the moving blade metal temperature by supplying and circulating air inside the moving blades, and discharging air after cooling into the gas flow path of the turbine as it is.
However, recently in gas turbine equipment, for the purpose of energy conservation and environmental maintenance, realization of high efficiency of a system has been required. As a means of realization of high efficiency, a closed circuit blade cooling system is used, which system has a constitution that a cooling medium (hereinafter referred to as a refrigerant) after cooling of the moving blades is all collected without discharging it into the turbine gas flow path as exhaust gas as it is and returned between the compressor and the combustor via the return line.
Thereby, not only the loss extracted from the compressor as a refrigerant is recirculated and made up but also the thermal energy received by turbine cooling is added to gas before combustion and hence a constitution that high efficiency improvement is available is realized.
Such a closed circuit blade cooling system or turbine is described in, for example, Japanese Patent Application Laid-Open 7-189740 and Japanese Patent Application Laid-Open 9-242563.
Meanwhile, in the closed circuit blade cooling turbine, a refrigerant to be supplied from the still side is generally supplied to the rotor via a single supply path without distinction of a refrigerant for the first stage moving blades (moving blades positioned on the uppermost stream side of main gas of the gas turbine) and a refrigerant for the second stage moving blades (moving blades positioned on the downstream side of the first stage moving blades) and also when the refrigerant is to be collected on the still side from the rotor after cooling each moving blade, it is collected via a single collection path without distinction of the refrigerant for the first stage moving blades and the refrigerant for the second stage moving blades. Therefore, the branch point of a refrigerant to be supplied to the first stage moving blades and the second stage moving blades and the junction of a refrigerant to be collected from the first stage moving blades and the second stage moving blades are located inside the rotor. Between the branch point and the junction in the rotor, a refrigerant supply flow path and a refrigerant collection flow path for the first stage moving blades and a refrigerant supply flow path and a refrigerant collection flow path for the second stage moving blades are installed and these flow paths have a plurality of parallel flow paths for refrigerant supply and a plurality of parallel flow paths for refrigerant collection which are connected to the respective refrigerant paths in the moving blades at each stage.
However, there are the following problems imposed in a conventional closed circuit blade cooling turbine.
Since main gas passing through the second stage moving blades does its work in the first stage moving blades, the temperature of main gas in the second stage moving blades is lower than that of the first stage moving blades. When the temperature of main gas at the outlet of the combustor is on the level of 1500xc2x0 C., the difference in the temperature of main gas between the first stage moving blades and the second stage moving blades is more than 200xc2x0 C. Even if the allowable metal temperature of the first stage moving blades is made higher than that of the second stage moving blades depending on the material characteristics such as the material kind, single crystal, polycrystal, and others, it is impossible to compensate for more than 200xc2x0 C. of difference in the temperature of main gas by the material and hence it is necessary that the first stage moving blades supply and cool a refrigerant at a flow rate higher than that of the second stage moving blades.
Inside the rotor, as mentioned above, the refrigerant flow path (refrigerant supply flow path and refrigerant collection flow path) for the first stage moving blades and the refrigerant flow path (refrigerant supply flow path and refrigerant collection flow path) for the second stage moving blades are installed. In this case, assuming that the flow resistance of the refrigerant flow path for the first stage moving blades and the flow resistance of the refrigerant flow path for the second stage moving blades in the moving blades and rotor are equal to each other, a refrigerant in the same amount flows through the first stage moving blades and second stage moving blades respectively.
However, by doing this, as mentioned above, an appropriate refrigerant flow rate cannot be distributed in the first stage moving blades and second stage moving blades which are different in the necessary refrigerant flow rate. Namely, if a necessary amount of refrigerant is supplied to the first stage moving blades, an excessive amount of refrigerant flows through the second stage moving blades and the thermal effect of the turbine is reduced. Inversely, if a necessary amount of refrigerant is supplied to the second stage moving blades, the refrigerant of the first stage moving blades is insufficient and the first stage moving blades exceed the allowable metal temperature.
On the basis of the aforementioned respects, even if the sectional area and resistance of the refrigerant supply flow path in each of the rotor and moving blades are estimated at the design stage and each refrigerant flow path is designed and manufactured on the basis of it so that an appropriate flow rate flows in the moving blades at each stage, actually variations are easily caused to each product and after assembly and manufacture, when the metal temperature of each of the first stage moving blades and second stage moving blades is deviated from the design value, it is necessary to adjust the flow rate distribution of a refrigerant to be supplied depending on the metal temperature of each of the first stage moving blades and second stage moving blades.
A refrigerant supplied to the rotor via the single supply path is branched to a refrigerant for the first stage moving blades and a refrigerant for the second stage moving blades in the rotor and the refrigerants after cooling the first stage moving blades and second stage moving blades join in the rotor and are collected outside the rotor via the single collection path. Therefore, it is necessary to adjust the refrigerant flow rate of each of the first stage moving blades and second stage moving blades and in this case, it is necessary to consider at what position of the refrigerant flow path the flow path resistance for flow rate adjustment is to be set.
In the general constitution of the rotor that the rotor is locked with bolts with a plurality of wheels and spacers overlapped in the axial direction, when a flow path resistor is installed inside the rotor, whenever the flow rate for the moving blades at each stage is to be adjusted, it is necessary to remove the locking bolts of the rotor and break down it and hence the operation is complicated extremely and the operation time and cost are increased. Therefore, it is a problem how to adjust the flow rate simply without breaking down the rotor.
An object of the present invention is to provide a closed circuit blade cooled turbine in which a refrigerant can be supplied to and collected from each of first stage moving blades and second stage moving blades having a necessary high refrigerant flow rate at an appropriate flow rate distribution.
Another object of the present invention is to provide a closed circuit blade cooling turbine in which a refrigerant flow rate to the moving blades at each stage can be simply adjusted without disassembling the rotor.
(1) To accomplish the above first object, the present invention provides a closed circuit blade cooling turbine having moving blades at a plurality of stages arranged in the flowing direction of main gas of a gas turbine and fixed to the outer periphery of a rotor, supplying a refrigerant at least to the first stage and second stage moving blades from the upstream side among the moving blades at the plurality of stages, and collecting the refrigerant after cooling without discharging it into main gas, wherein the turbine, inside the rotor, has a branch point of the refrigerant supply path for the first stage moving blades and the refrigerant supply path for the second stage moving blades and a junction of the refrigerant collection path for the first stage moving blades and the refrigerant collection path for the second stage moving blades, and the refrigerant supply path and refrigerant collection path for the first stage moving blades and the refrigerant supply path and refrigerant collection path for the second stage moving blades have a plurality of parallel flow paths for refrigerant supply and a plurality of parallel flow paths for refrigerant collection to be connected to the respective refrigerant paths in the moving blades at each stage between the branch point and the junction, and the sum of minimum sectional areas of any parts of the plurality of parallel flow paths for refrigerant supply for the second stage moving blades and the plurality of parallel flow paths for refrigerant collection and the respective refrigerant flow paths in the second stage moving blades is smaller than the sum of minimum sectional areas of any parts of the plurality of parallel flow paths for refrigerant supply for the first stage moving blades and the plurality of parallel flow paths for refrigerant collection and the respective refrigerant flow paths in the first stage moving blades.
Thereby, for the first stage moving blades and second stage moving blades which are greatly different in the necessary refrigerant flow rate, a refrigerant can be supplied and collected respectively at an appropriate refrigerant flow rate distribution.
(2) To accomplish the above first object, the present invention provides a closed circuit blade cooling turbine having the refrigerant supply flow path and refrigerant collection path for the first stage moving blades, the refrigerant supply flow path and refrigerant collection path for the second stage moving blades, and a plurality of parallel flow paths for refrigerant supply and a plurality of parallel flow paths for refrigerant collection between the branch point and the junction, wherein at any part of the plurality of parallel flow paths for refrigerant supply for the first stage moving blades, the plurality of parallel flow paths for refrigerant collection, and the respective refrigerant flow paths in the first stage moving blades, the first metal fittings having an internal flow path are arranged, and at any part of the plurality of parallel flow paths for refrigerant supply for the second stage moving blades, the plurality of parallel flow paths for refrigerant collection, and the respective refrigerant flow paths in the second stage moving blades, the second metal fittings having an internal flow path are arranged, and the sum of sectional areas of the internal flow paths of the second metal fittings is smaller than the sum of sectional areas of the internal flow paths of the first metal fittings.
Thereby, for the first stage moving blades and second stage moving blades which are greatly different in the necessary refrigerant flow rate, a refrigerant can be supplied and collected respectively at an appropriate refrigerant flow rate distribution.
(3) To accomplish the above first object, the present invention provides a closed circuit blade cooling turbine having the refrigerant supply flow path and refrigerant collection path for the first stage moving blades, the refrigerant supply flow path and refrigerant collection path for the second stage moving blades, and a plurality of parallel flow paths for refrigerant supply and a plurality of parallel flow paths for refrigerant collection between the branch point and the junction, wherein at any part of the plurality of parallel flow paths for refrigerant supply for the second stage moving blades, the plurality of parallel flow paths for refrigerant collection, and the respective refrigerant flow paths in the second stage moving blades, a means for adjusting the internal flow resistance is installed.
Also thereby, for the first stage moving blades and second stage moving blades which are greatly different in the necessary refrigerant flow rate, a refrigerant can be supplied and collected respectively at an appropriate refrigerant flow rate distribution.
(4) Furthermore, to accomplish the above first object, the present invention provides a closed circuit blade cooling turbine having the refrigerant supply flow path and refrigerant collection path for the first stage moving blades, the refrigerant supply flow path and refrigerant collection path for the second stage moving blades, and a plurality of parallel flow paths for refrigerant supply and a plurality of parallel flow paths for refrigerant collection between the branch point and the junction, wherein at any part of the plurality of parallel flow paths for refrigerant supply for the second stage moving blades, the plurality of parallel flow paths for refrigerant collection, and the respective refrigerant flow paths in the second stage moving blades, the third metal fittings having an internal flow path are arranged and the third metal fittings have a means for adjusting the internal flow resistance.
Also thereby, for the first stage moving blades and second stage moving blades which are greatly different in the necessary refrigerant flow rate, a refrigerant can be supplied and collected respectively at an appropriate refrigerant flow rate distribution.
(5) To accomplish the above first and second objects, the present invention provides a closed circuit blade cooling turbine having the refrigerant supply flow path and refrigerant collection path for the first stage moving blades, the refrigerant supply flow path and refrigerant collection path for the second stage moving blades, and a plurality of parallel flow paths for refrigerant supply and a plurality of parallel flow paths for refrigerant collection between the branch point and the junction, wherein the sum of minimum sectional areas of any parts in the neighborhood of the connections of the plurality of parallel flow paths for refrigerant supply for the second stage moving blades and the respective refrigerant flow paths in the second stage moving blades and in the neighborhood of the connections of the plurality of parallel flow paths for refrigerant collection for the second stage moving blades and the respective refrigerant flow paths in the second stage moving blades is smaller than the sum of minimum sectional areas of any parts in he neighborhood of the connections of the plurality of parallel flow paths for refrigerant supply for the first stage moving blades and the respective refrigerant flow paths in the first stage moving blades and in the neighborhood of the connections of the plurality of parallel flow paths for refrigerant collection for the first stage moving blades and the respective refrigerant flow paths in the first stage moving blades.
Thereby, for the first stage moving blades and second stage moving blades which are greatly different in the necessary refrigerant flow rate, a refrigerant can be supplied and collected respectively at an appropriate refrigerant flow rate distribution and the refrigerant flow rate to the moving blades at each stage can be adjusted simply without breaking down the rotor.
(6) To accomplish the above first and second objects, the present invention provides a closed circuit blade cooling turbine having the refrigerant supply flow path and refrigerant collection path for the first stage moving blades, the refrigerant supply flow path and refrigerant collection path for the second stage moving blades, and a plurality of parallel flow paths for refrigerant supply and a plurality of parallel flow paths for refrigerant collection between the branch point and the junction, wherein at any parts in the neighborhood of the connections of the plurality of parallel flow paths for refrigerant supply for the first stage moving blades and the respective refrigerant flow paths in the first stage moving blades and in the neighborhood of the connections of the plurality of parallel flow paths for refrigerant collection for the first stage moving blades and the respective refrigerant flow paths in the first stage moving blades, the first metal fittings having an internal flow path are arranged, and at any parts in the neighborhood of the connections of the plurality of parallel flow paths for refrigerant supply for the second stage moving blades and the respective refrigerant flow paths in the second stage moving blades and in the neighborhood of the connections of the plurality of parallel flow paths for refrigerant collection for the second stage moving blades and the respective refrigerant flow paths in the second stage moving blades, the second metal fittings having an internal flow path are arranged, and the sum of sectional areas of the internal flow paths of the second metal fittings is smaller than the sum of sectional areas of the internal flow paths of the first metal fittings.
Also thereby, for the first stage moving blades and second stage moving blades which are greatly different in the necessary refrigerant flow rate, a refrigerant can be supplied and collected respectively at an appropriate refrigerant flow rate distribution and the refrigerant flow rate to the moving blades at each stage can be adjusted simply without breaking down the rotor.
(7) Furthermore, to accomplish the above first and second objects, the present invention provides a closed circuit blade cooling turbine having the refrigerant supply flow path and refrigerant collection path for the first stage moving blades, the refrigerant supply flow path and refrigerant collection path for the second stage moving blades, and a plurality of parallel flow paths for refrigerant supply and a plurality of parallel flow paths for refrigerant collection between the branch point and the junction, wherein at any part in the neighborhood of the connections of the plurality of parallel flow paths for refrigerant supply for the second stage moving blades and the respective refrigerant flow paths in the second stage moving blades and in the neighborhood of the connections of the plurality of parallel flow paths for refrigerant collection for the second stage moving blades and the respective refrigerant flow paths in the second stage moving blades, a means for adjusting the internal flow resistance is installed.
Also thereby, for the first stage moving blades and second stage moving blades which are greatly different in the necessary refrigerant flow rate, a refrigerant can be supplied and collected respectively at an appropriate refrigerant flow rate distribution and the refrigerant flow rate to the moving blades at each stage can be adjusted simply without breaking down the rotor.
(8) To accomplish the above first and second objects, the present invention provides a closed circuit blade cooling turbine having the refrigerant supply flow path and refrigerant collection path for the first stage moving blades, the refrigerant supply flow path and refrigerant collection path for the second stage moving blades, and a plurality of parallel flow paths for refrigerant supply and a plurality of parallel flow paths for refrigerant collection between the branch point and the junction, wherein at any part in the neighborhood of the connections of the plurality of parallel flow paths for refrigerant supply for the second stage moving blades and the respective refrigerant flow paths in the second stage moving blades and in the neighborhood of the connections of the plurality of parallel flow paths for refrigerant collection for the second stage moving blades and the respective refrigerant flow paths in the second stage moving blades, the third metal fittings having an internal flow path are arranged and the third metal fittings have a means for adjusting the internal flow resistance.
Also thereby, for the first stage moving blades and second stage moving blades which are greatly different in the necessary refrigerant flow rate, a refrigerant can be supplied and collected respectively at an appropriate refrigerant flow rate distribution and the refrigerant flow rate to the moving blades at each stage can be adjusted simply without breaking down the rotor.
(9) In (2), (4), (6) and (8) mentioned above, the first and second metal fittings or the third metal fittings are preferably supply members or collection members which are installed so as to prevent a refrigerant from leaking from the rotor and the gap between the first stage moving blades and the second stage moving blades.
Thereby, using the supply members or collection members installed so as to prevent a refrigerant from leaking, the refrigerant flow rate can be adjusted.
(10) In (1) to (8) mentioned above, furthermore, in the refrigerant flow path at least on one of the still side which is a supply source of the aforementioned refrigerant and the still side which is a collection destination of the aforementioned refrigerant, a means for adjusting the flow resistance is installed.
By doing this, a large adjustment margin of the refrigerant flow rate of not only the second stage moving blades but also the first stage moving blades can be obtained.
(11) To accomplish the above first object, the present invention provides a closed circuit blade cooling turbine having, inside the rotor, a branch point of the refrigerant supply path for the first stage moving blades and the refrigerant supply path for the second stage moving blades and a junction of the refrigerant collection path for the first stage moving blades and the refrigerant collection path for the second stage moving blades, wherein so that the pressure loss generated in the refrigerant flow path and refrigerant collection flow path for the second stage moving blades can be made larger than the pressure loss generated in the refrigerant flow path and refrigerant collection flow path for the first stage moving blades, the respective flow paths are formed.
Also by doing this, for the first stage moving blades and second stage moving blades which are greatly different in the necessary refrigerant flow rate, a refrigerant can be supplied and collected respectively at an appropriate refrigerant flow rate distribution.